State-of-the-art electric energy conversion relies on a three-phase power network with alternating currents (AC) at 50 Hz or 60 Hz frequency and a voltage levels ranging from several hundreds of Volts to hundreds of thousands of Volts. The conversion of rotating mechanical energy into electric energy and vice versa is done by generators and by motors respectively. Those rotating machines can be divided into asynchronous and synchronous apparatuses. The three-phase windings of such machines comprise Copper strands which after Roebelling form a conductor. The windings also require groundwall insulation, especially in the slot section. An assembly consisting of a Roebel conductor in the center and of surrounding groundwall insulation is commonly referred to as a stator bar.
When making stator bars, the conductor needs to be shaped. This disclosure uses the terms shaping stator bars and shaping the conductors inside a stator bar interchangeably. Unless otherwise indicated, the expression shaping a stator bar means shaping the conductors inside a stator bar.
The process of shaping is carried out in several steps involving a plurality of workbenches and gates. Typically, the first stage and the second stage bending are carried out at gate. Subsequently, the main involute is shaped Also, the ends of the stator bar are shaped, then the bar is consolidated and finally lugs at the end of the stator bar are brazed onto the bar. The purpose of the lugs is electric contact between the stator bars of a power generator. Another purpose of the lugs is electric contact to the terminals of the generator.
A number of approaches are mentioned in literature that try and overcome the above issues. U.S. Pat. No. 7,530,161 discloses a modular quick-form tooling system and stator bar set-up method. According to this application, a plurality of bend-forming tools 32, 33 are mounted on a support structure 31. A stator bar 20 is then inserted in between a guide portion 35 and the bend-forming tools 32, 33 to shape the stator bar 20.
U.S. Pat. No. 7,275,300 discloses a process for rewinding stator bars of a power generator. The process disclosed in U.S. Pat. No. 7,275,300 involves a quick form shown on FIG. 4 of the specification. The form is used to define the shapes of replacement stator bars during manufacturing. It fixates the core section 40 of a stator bar to end arm fixtures 42 on either end of the core section 40. The form also provides a lever to assist the bending process.
Yet another approach is disclosed on the internet http://www.vincent-industrie.com/en/activities/electrical/88-turbo-bars-forming-machine-tbfm.html. The machine disclosed therein uses a forming head and an involute support clamp to form stator bars for hydro- and for turbogenerators. The machine uses brushless motors to allow for accurate positioning of the stator bars during the forming process. Also, the stator bar forming machine is able to automatically load and unload bars in order to save time.
The established processes for making stator bars have several disadvantages. The sourcing time for the tool used for shaping the main involute is several weeks. Also, the process for setting up and adjusting that tool is known to be time-consuming. The process of shaping a generator bar is known to take as long as 4.5 (four and a half) hours.
The present disclosure is oriented towards providing the aforementioned needs and towards overcoming the aforementioned difficulties.